Building on recent research on the Rhine River between France and Germany, a research team based in Strasbourg has published a review of scientific literature on projects to restore channel complexity downstream of dams. While dam removal has attracted enormous attention in recent years, with notable successes on the Elwha River, the reality is that most dams are here to stay and most river reaches in the developed world are downstream of dams. As these dams capture sediment, they create conditions of sediment deficit in many river reaches downstream. This review found relatively few studies documenting projects to restore sediment supply via gravel augmentation and fewer still via restoration of channel erosion processes below dams (mostly examples from northern Europe). Biological monitoring shows benefits from these projects, whose increasing popularity reflects growing interest in restoration of fluvial process, and an evolving perspective towards adaptive or coupling management approaches to promote the recovery of natural processes in rivers below many dams and thus to improve ecological response.
The paper, Restoring fluvial forms and processes by gravel augmentation or bank erosion below dams: A systematic review of ecological responses, by Cybil Staentzel et al. is available for free download here until 01 February 2020.